Reversible electronic telegraph extensors



Nov. 4, 1958 A. E. CANFORA E AL 2,859,278

REVERSIBLE ELECTRONIC TELEGRAPH EXTENSORS Filed Aug. 31. 1953 6 Sheets-Sheet 1 FREQUENCY DIV/DER PULSE T '7 CHAIN jf SER-SEF. our I MARK GATE [j L-"- AND 1/ BANK 5TART- sToP 5 23 1 O r\ I .52 EMF/V7 OSCILLATOR GATE my:

5 N11 {3/} STA/FF START STOP TE 6'0/VTROL GA 27 SER-SER IN j! INPUT AMPLIFIER POWER OUTPUT A MPL/F/ER SEP -5EA PLUG O O 3 6 .9 l2 l5 l8 2/ 24 2 7 30 33 IN VEN TORS SAMUEL JHA R/N F, 3 BY ARTHUR E. CA/VF'ORA A TTOEWEY Nov. 4, 1958 A. E. CANFORA ETAL 2,859,273

REVERSIBLE ELECTRONIC TELEGRAPH EXTENSORS Filed Aug. 51, 1953 6 Sheets-Sheet 2 1N VEN TOR5 SAMUEL SI/AE/N Piazza 4 7'TORNE) Nov. 4, 1958 A. E. CANFORA ETAL 2,859,278

REVERSIBLE ELECTRONIC TELEGRAPH EXTENSORS s Sheets-Sheet 3 Filed Aug. 31. 1953 Z 4 v93 if; 96 53/ 4/ CURRENT OUTPUT INVENTORS SAMUEL SHAH/IV ART/1w? E. C'AA/FOAA A 7' TOE/YE Y REVERSIBLE ELECTRONIC TELEGRAPH EXTENSORS Arthur Eugene Canfora and Samuel Sharin, Brooklyn, N. Y., asslgnors to Radio Corporation of America, a corporation of Delaware- Application August 31, 1953,, Serial No. 377,618

16 Claims. (Cl'. 1 7853.1)

neously or sequentially element after element. An n-ele- Y ment simultaneous signal is construed to be one inwhich n signal elements appear simultaneously on rt separate circuits, and a sequential signal is construed to be one in which n elements appear on 11 separate circuits element after element. A circuit arrangement for transposing from serial representation to a separate presentation is termed by those skilled in the art as ser-sep, and a circuit arrangement for carrying out the reversed process is known as a sep-ser. Similarly circuit arrangements limited to serial and simultaneous. presentations are known as ser-sim or sirn-ser, and circuit arrangements specifically limited to serial and sequential presentation are known as ser-seq and seq-ser.

In multiplex telegraph operations there has long been used a piece of apparatus called an extensor capable of transposing a code character signal appearing serially element after element over a single circuit into the same code character signal with the elements appearing sequentially or simultaneously over separate circuits, and another piece of apparatus, separate and distinct from the former, for transposing a code character represented by simultaneously appearing signal elements into one represented by signal elements appearing serially over a single circuit. Because the prior art extensor apparatus has been mainly in paratus, the first piece of apparatus mentioned was capable only of transposing a serial signal to a sequential signal. The second piece of apparatus, also called an extensor, was limited in use to transposing simulta neously appearing signals into a serial signal. It is sometimes desirable that apparatus be available which will be capable of handling a separate signal either in simultaneous form or in sequential form. Although it has been suggested that electronic circuits be usedfor this purpose, up until the present time there have been no suggested arrangements whereby a single piece of apparatus can be made to transpose serial signals into separate form, whether sequentially or simultaneously appearing, and with a simple switching action be converted to transpose the separate signal into a. serial signal. In the interest of simplicity, however, it is highly advantageous to be able to provide the operating technicians with apparatus which can be used interchangeably by the manipulation of a simple. switch or other control.

*United States Patent"() the form of mechanical ap- An object of the invention is to. provide improved electronic means for transposing separate signals into serial signals and conversely to transpose serial signals into separate signals, whether simultaneously appearing or sequentially appearing separate signals are involved. Another object of the invention is to provide an im proved electronic circuit arrangement selectively capable of transposing a serial signal to a separate signal .or a separate signal into a serial signal. v

A furtherobject of the invention. is to provide. an improved all-electronic extensor which will produce a uniform output signal regardless of. variations inthe input signals. I

Still another object of the invention is to provide an all-electronic extensor which will automatically transpose from serial to separate or from separate to serial as required upon being interconnected with the associated appar'atus. a

The objects of the invention are attained in an'f'all electronic circuit arrangement having a serial input circuit, a plurality of separate output terminals, a; plurality of separate input terminals and a serialoutput circuit interconnected by means of electronic gating circuits. The gating circuits are operated in properly timedsequence under the control of timing waves developed in a frequency divider chain which is activated by a start-stop oscillator under. the influence of start-stop control and start gate circuits responsive to the inputLsignal. Switchingmeans are interposed between the'circuits to provide proper operation when serially'appearing elements are applied to the serialinput circuit to produce sequentially appearing elements at the separate output terminals, and selectively to produce serially appearing signal elements in response to the application of simultaneously appearing input elements to the separate input terminals. Storage means may be addedto convert the sequentially appearing signal elements into simultaneously appearing elements, it necessary.

In serial to separate operation, referred to as 'ser-sep operation, an n-element serial signal is presented to an amplifier input. The signal is amplified and filtered. Thereafter the filtered and amplified signals are simultaneously presented to a start gate and a serial input gate. Under normal conditions the start gate is opened with the first transition to space. The opening of the start gate will send the pulse to a startstop oscillator, causing the oscillator to operate for one cycle. Thefirst cycle or pulse from the oscillator is applied to the input of a timing wave generator, preferably a frequency divider chain, to produce a plurality of harmonically related timing square waves. The first output cycle of the frequency divider chain is applied'to the start gate to prevent further signal transitions of the same character from being applied to the start-stop oscillator and is also applied to the startstop control to maintain the startstop oscillator in oscillation and therebycontinue'a'pplying pulses to the frequency divider chain. While this action is taking place, the serially. appearing signal elements are being applied to a serial input gate. Ouput pulsesfrom'thestart-stop oscillator are also applied to this serial input gate; The serial input gate is arranged so that the serially appearing input signal elements condition the serial input gate to permit certain ones said given nature, the serial input gateremains closed to the pulses from the start-stop oscillator. Pulses from the start-stop oscillator which are permitted to pass through the serial input gate are applied to a series of signal element gates'which are operated in timed sequence under control of the timing waves developed by the frequency divider chain. The second cycle or pulse from the frequency divider chain causes the gate corresponding to the first signal element to open and, if the signal element applied to the serial input amplifier is of. given nature,- there is an output indicated at the separate output terminal connected to that gate. But, if the serial input signal is of opposite nature, no output will appear at that separate output terminal and .so on. The frequency of the start-stop oscillator is selected so that the element gates open when the corresponding elementofthe applied signal'train is pre- 'sented Thetbird, fourth, cycles from the frequency divider chain open the gates corresponding to the second through the nth elements in order, whereupon elements two through 11 of the serially appearing signal are observed sequentially at the separateoutput' terminals in exactly the same manner as described for the first element .of the serial signal train. The last pulse (n+2) from the start-stop oscillator is used: (1) To reset the binary or frequency divider chain tothe initial condition; f (2) To reset and lock up the start-stop oscillator so at no further. pulses are applied to the frequency divider chain;

(3) To send a convert pulse to the associated apparatus receiving the simultaneous signal after trans posing; and y w (4) To condition the start gate to open upon receipt of the next transition to space.

In separate-to-serial operation, sometimes called sepser operation, the n signal elements are usually presented simultaneously from an electro-mechanical tape sensor or transmitting distributor to the separate input terminals; After the signal elements are presented, a start pulse from an external source is sent to the start gate, which is normally conditioned to open upon the receipt of a start pulse. The start gate, the start-stop control,the start-stop oscillator, and the, frequency divider chain operate as described above in connection with ser-sep operation. Before the start pulse --was introduced, another gate was open and a marking-element was sent through a power output am plifierto the utilization circuit. The first pulse from the start-stop oscillator is used to close the mark gate, causing a spacing condition to be presented atthe output of the power output amplifier. The first pulsefrom the frequency divider chain is used to condition the startstop oscillator to continue oscillating and thereby con- .tinue operation of the frequency divider chain. The signal element gates correspondingto the n elements are opened in order whereby the signal elements presented .on the n simultaneous input terminals are in turn presented at the single serial output line terminal. The last pulse (n+2) from the start-stop oscillator and the frequency divider chain perfor the same functions described above for ser-sep operation with the exception that an output reset pulse is developed instead of a convert pulse and an additional gate, the mark gate, is opened when no signal ispresent.

In accordance with another aspect of the invention, sep-ser and conversely is prefswitching from ser-sep to erably accomplished by the use of separate plugs attached to the various pieces of apparatus to be interconnected; the plugs having diiferent connections to the and up to n+1 pulses or accompanying drawing in which:

extensor automatically selecting the mode of operation.

If desired however, this switching could also be accomplished by the use of a multiple-pole double-throw switch.

In order that the invention may be more clearly understood and readily put to practical use, a circuit ara rangementembodying the invention is hereinafter de- 1 is arranged to such an extensor is likely to be put.

Fig. l is a functional diagram of a reversible extensor I circuit arrangement according to the invention;

Fig. 2 (sections a and b being taken together) is-a schematic diagram of a according to the invention:

Fig. 3 is a diagram of plug connections suggested for use with the circuitry of Fig. 2 for performing the switching function automatically to convert the circuit arrangement from ser-sep to sep-ser operatiomand Figs. 4, 5, and 6 are graphical representations of wave forms produced during the operation of the circuit arrangement shown schematically in Fig. 2.

Referring to Fig. 1, there is shown a functional diagram of a circuit arrangement according to the invention wherein a serial signal element train may be applied to input terminals 11 for subsequent presentation at a plurality of separate output terminals 13. Alternately, a plurality of signal elementsrepresenting a code character may be applied individually to a plurality of separate input terminals 15 and a signal element train obtained at a serial output terminal 17. A bank 21 of electronic gating circuits, which are operated in properly timed sequence under the control of a timing wave gen? erator in the form of a frequency divider chain 23, couple the desired serial circuit terminals with the corresponding separate circuit terminals in timed succession.

' The frequency divider chain 23 is activated by a startstop oscillator 25 under the influence of a start-stop control circuit 27 and a start gate 29 in response to a transition of the signal or a start pulse as obtained from an input amplifier 33. The convert pulse generator'35 provide a pulse at the terminals 37 props erly timed for use with associated apparatus. A power output amplifier 39 having an output terminal 41 is pref: erably interposed in the circuit arrangement to provide sufficient drive for the usual requirements to which This amplifier 39 may be used to amplify a signal applied at the drive pulse input terminal 43. Switching means S are interposed between the input amplifier 33 and the serial input gate 31; between the serial input gate 31 and the element gate bank 21; and between the terminal 43 and the amplifier 39 to transpose serially appearing elements applied at the serial input terminal 11 into sequentially appearing elements at the separate output terminals 13 with the switching means S in the position indicated in Fig. 1. Ser-sep operation, Figure I In this serial-to-separate operation, or ser-sep operation,

an n-element serial signal .is presented to the input tere' The signal is amplified and filtered in the and simultaneously presented to the start tions of a given character from being applied to the start-' stop oscillator 25 and to the start-stop control to condition the oscillator 25 to continue oscillating. The startstop control 27 is responsive to the operation of the chain 23 to maintain the oscillator 25 in oscillation.-.

While this action is taking place, the serially appearing signal elements and output pulses from the start-stop oscil-' later 25 are also applied to the serial input gate 31. This serial input gate 31 is arranged so that the serially appearing input signal elements condition the serial input gate 31 to permit certain pulses obtained from the startstop oscillator 25 to pass through. If the serially appearthe pulse to the start-stop oscillator.

practical circuit arrangement 31.' ,Under normal coning signal elements are marking, a pulse is passed'irom the start-stop oscillator 25 through the serial input gate 31. If, however, the serial input signal elements are spacing, the serial input gate 31 remains closed to the pulses from the start-stop oscillator 25. Pulses from the start-stop oscillator 25 which are permitted to pass through the serial input gate 31 are applied to the individual signal element gates of the bank 21 which gates are operated in timed sequence under control of the timing waves developed by the frequency divider chain 23. The second cycle or pulse from the frequency divider chain 23 causes the gate corresponding to the first signal element to open. If the signal element applied to the serial input amplifier is marking, there is an output indicated at the separate output terminal connected to that gate. But if the serial input signal is spacing, no output will appear at that separate output terminal and so on. The final pulse (n+2) from the start-stop oscillator 25 is used to reset the circuit arrangement to the initial conditions.

Sep-ser operation, Figure 1 For separate-to-serial operation, or sep-ser operation the switching means S is thrown to connect the separate input terminals 15 to the signal element gate bank 21', the gate bank 21 to the signal output terminal 17 and thence to the power output amplifier 39. The n signal elements are usually simultaneously presented from a transmitting distributor to the separate input terminals 15. A start pulse from an external source is applied to the input terminals 11, amplified in the amplifier 33 and applied to the start gate 29, which is normally conditioned to open upon the receipt of this start pulse. The start gate 29, the start-stop control 27, the start-stop oscillator 25 and the frequency divider chain 23 operate as described above in connection with ser-sep operation. Before the start pulse was introduced, a mark gate in the bank 21 was open and a marking-element was applied to the power output amplifier 39 over the common circuit through the terminal 17 The first pulse from the start-stop oscillator 25 serves to close the mark gate, causing a spacing condition to be presented at the output terminal 41 of the power output amplifier 39. The first pulse from the frequency divider chain 23 is used to condition the start-stop oscillator 25 to continue oscillating and thereby continue operation of the frequency divider chain 23. The signal element gates of the bank 21 corresponding to the n-elements are opened in order, whereby the signal elements presented on the simultaneous input terminals are in turn presented on the single output line terminal 17. The mark gate is open when no signal is present.

The schematic diagram of a practical circuit arrangement along the lines of the functional diagram of Fig. 1 is given in Fig. 2. The action of the extensor as shown in this specific circuit arrangement for five element code is centered about the opening of the signal element gates 211 through 21-5 of the gate bank 21. Obviously, any fixed length code can be used in the practice of the invention as the necessary minor changes in circuitry required will be immediately suggested to those skilled in the art. The action of the circuit arrangement insofar as the gating circuits are concerned is exactly the same for ser-sep or sep-ser operations with the exception of the source of the start pulse. The signal element gates 21-1 through 21-5 must be open one at a time in numerical order and no two gates may be open at any onetime. Another gate, the mark gate 21-M, is active in the sepser operation only and remains idle in ser-sep operation.

For the moment assume that a start pulse has been applied to the grid of the start gate tube V4B. A negative pulse will be developed at the anode of the start gate tube V4B which is applied to the anode of an oscillator tube V7B. The start-stop oscillator 25 comprises two tubes V7A and V7B cross coupled in monostable reciproconductive circuit configuration. The start-stop oscillator 25 is essentially a frequency multivibratoraud is a; variation of the multivibrator described in the copending U. S. application Serial No. 372,891, filed on August 7, 1953 on behalf of Samuel Sharin, Arthur E. Canfora, Hajime James Kishi and Anthony Liguori and now U. S. Patent No. 2,762,917, issued September 11, 1956. Briefly, the start-stop oscillator 25 comprises two triode vacuum tubes V7A and V7B cross coupled in monostable reciproconductive circuit fashion. As employed herein, theterm reciproconductive circuit is construed to include all tube regenerative circuit arrangements in which conduction alternates in one or the other tube. The astable reciproconductive circuit is synonymous with the broad term multivibrator, which term is herein limited to the astable reciproconductive circuit. The monostable reciproconductive circuit is one which requires one triggering pulse to switch from the single stable state of conduction to the single unstable state and return. This circuit is sometimes referred to as a self-restoring trigger circuit and more often referred to as a one-shot multivibrator. The bistable reciproconductive circuit, which is one which requires two triggering pulses to switch from one stable state of conduction to the other and return, is sometimes termed a lockover circuit, bistable multivibrator or a binary. As used herein the term binary reciproconductive circuit is construed to mean such a circuit having a single input and which alternates'conduction upon the application of successive pulses to the single input circuit. Clamping diodes VGA and V6B are connected between the anodes of the tubes V7A and V7B respectively and ground. A triode vacuum tube VSA is connected between the anode and grid of tube V7A. In a similar manner, a triode vacuum tube VSB is connected between the anode and grid of tube V7B.

The frequency of operation of the multivibrator startstop oscillator 25 is controlled by the tubes V5A and V53 which operate to apply biasing voltages to the grids of tubes V7A and V7B, respectively, according to the values of the capacitors 45 and the resistors 47. The start-stop control circuit comprises the triode vacuum tube V4A which is normally conducting and is connected: between the anode of the trigger tube VSA and the point of fixed reference potential or ground. The application of the start pulse to the grid of the start gate tube V4B and subsequent application of the negative pulse to the anode of the reciproconductive tube V7B causes the monostable reciproconductive circuit to be triggered for one complete cycle of operation. The output of the start-stop oscillator 25 taken from the anode of the reciproconductive tube V7B is applied to the input terminal of the frequency divider chain 23. The frequency divider chain 23 comprises three binary reciproconductive circuits 51, 52, and 53 connected together in conventional counting chain fashion. The application of the negative pulse from the anode of the start-gate tube V4B to the startstop oscillator 25 and to the input of the reciproconductive circuit 51 advances the frequency divider chain one step. The subsequent output of the frequency divider chain 23 at the busses 3 and 5 is applied through the resistors 55 and 56 to the grid of the start gate tube V4B to close the start gate 29 to any further pulses until the succeeding character is applied. Other output potentials from frequency divider chain 23 appearing at busses 2, 3 and 5 are applied through resistors 57, 58 and 59 to the grid of the start-stop control tube V4A cutting this tube oil. Blocking of the start-stop control tube V4A removes the holding voltage applied to the oscillator 25 and releases the start-stop oscillator 25 to run freely and v advance the frequency divider chain 23 in the normal counting mode.

The output of the start-stop oscillator 25 as it. appears atthe anode of the tube V7B is a square wave as shown in Fig. 4, line 403. The wave forms at the anodes of tubes VIA and V1B, comprising the reciproconductive with the tubes circuit 51, areas shown at line 404 and VlB are shown in Fig. 4, lines and V1B-out of their sockets; The'output of the oscillator 25 is differentiated by the capacitor 61 and resistor "62, or by the capacitor 63 and resistor 64 of the reciproconductive circuit 51. The diode D1 eliminates the posi- -tive pulses resulting from this differentiation. These diferentiated pulses trigger the reciproconductive circuit 51 and the results as seenat the anodes of the tubes VIA 405 and 406. Lines 407 to 410 of Fig. 4 represent the wave forms at the anodes of the reciproconductive circuits 52 and 53 as the frequency divider chain 23 continues to divide in the well The frequency divider chain 23 continues to function until the anode of the tube V3B makes the negative transition. This transition is differentiated by a capacitor 65 and the associated resistance components and presented to the cathode of tube VIA which triggers the reciproconductive circuit 51. This operation results-in the pulse shown in Fig. 4 at time :13 on lines "405 and 406. At the exact same time the output potentials from the frequency divider'chain 23 appearing at busses 2, 3 and 5 are applied through the resistors 57, 58 and 59 to the grid of the start-stop control tube V4A causing this tube to conduct. Conduction of tube V4A causes a holding voltage to be applied to the oscillator 25' preventing anyfurther reciproconductive action. The

known manner.

convert pulse generator 35 comprising the tube V9B is coupled tobus 5 for producing a pulse at the output terminal 37 in proper timed relationship for use by subsequent utilization apparatus. By means of a capacitor 67 and a diode D4 the output of the tube V9B is applied to the gridof the reciproconductive tube V7B to force the monostable reciproconductive circuit back to the -""stablestate of conduction, thereby increasing the accuracy of the operation of the circuit arrangement. The reciproconductive circuits 51-53 will then be in the conditions of conduction shown at the time tl3 in Fig. 4, lines 405-410. The anodes of the tubes V1A through V3B of the reciproconductive circuits 51-53 are connected by means of the busses 16 and coincidence resistors 7187 to the grids of the mark gate 21M and the signal element gates 21-1 through 21-5 comprising the tubes V9A, V8B, LV10A, V10B, VllA and VllB, in such permutations as to cause the gates 21 M through'21-5 to open in timed succession, at a rate depending on the frequency of the start-stop oscillator 25. The grid voltages on the various gates 21M through 21-5 are shown in Fig. 4 lines 411-416.

The potentials on the grids of the tubes V813 and 'V10AV11B of the signal element gates 21-1 through 21-5 are shown in Fig. 4, lines 411-415. The potential on the grid of the tube V9A constituting the mark gate 'I21-M is shown in line 416. The mark gate 21-M and the start gate 29 are open before the start pulse comes in at the time t At the time t the mark and start gates "close and the signal element gates 21-1 through 21-5 remain closed until the time 1 This period corresponds 'to the start pulse of the S-unit printer code. From the "time t until the time t the first signal element gate 21-1 is open: the gates 21-2 through 21-5 remaining closed. From the time t to the time 1 the second signal element gate 21-2 is open: the other gates remaining closed. The "last signal element gate 21-5 is open from the time t "to At the time r the mark gate 21-M and the start gate 29 open and remain open until the next start pulse ;comes in. This latter period corresponds with the stop ;-pulse of the five-unit printer code.

' f Ser-sep operation, Figure 2 With the switches set as shown in Fig. 2 the circuit farrangement is set for serial to separate, or sersep, op- ;eration, A serially appearing train of signal pulses is applied to the terminals 11-1 and 11-2 from a source of such signals,.which source is usually an electromechani- "cal transmitting distributor or the like. This transmitting 8 distributor is arranged so that the terminals II-I'and -1l-2 are shortcircuited to form mark and held open to form spacing while a marking signal element will apply a negative potential derived comprising the resistors and 91 to the grid of the tube -V12A, to block the tube. Obviously the same keying could be accomplished by applying a potential negative with respect to ground to the terminal 11-1 for the marking signal elements and leaving the terminal open for spacing elements. The terminals 11-1 and 11-2 are normally closed, the start gate 29 is conditioned a positive pulse. A train of serially appearing signalelements comprising marking and spacing elements is then introduced at the terminals 11-1 and 11-2. At the time 2 corresponding to the transition between the stop pulse the grid ofthe triode tube V4B constituting the start gate 502 with pulses riding the 29 is shown in Fig. 5, line causes the start gate tube D. C. level. This first pulse V4B to conduct and deliver a in line 503, to the start-stop oscillator 25. Starting the oscillator 25 will cause the gates 21-1 through 21-5 'to open as previously described. The opening of the gates with respect to the timing of the signal train and the start gate 29 can be seen by referring to Fig. 5, lines 505-509.

In the meantime the input signal which is shown in Fig. 5, line 501', has been applied to the grid of a further amplifier tube V13A. The cathode of the tube V13A, which is connected as a cathode follower, is coupled to the cathode of the triode tube V8A forming the serial input gate 31. Before the signal elements are applied to the grid of the cathode follower tube V13A, both the grid and the cathode of the serial gating tube V8A are at relatively high potential. Spacing signal elements raise the grid of the cathode follower tube V13A. This subsequently tends to raise the cathode of the serial gating tube V8A still higher than before so that the negative pulses from the start-stop oscillator 25 applied to the grid of the gating tube V8A and no pulses will be 21-1 th.rough 21-5. Input marking signal elements will block the cathode follower V13A, tending to lower the cathode so that any negative pulse from the start-stop oscillator 25 applied to the grid of the serial gating tube V8A will cause the cathode of the serial gating tube V8A to be clamped to ground through the diode D5 and apply in response to a pulse negative with respect to ground to Such a negative pulse is ob- .open the first signal gate. tained from the start-stop oscillator 25 as shown in Fig. 5, line 504, and a negative pulse is then seen at the terminal l3-1 as shown in Fig. 5, line 510. The first signal element gate 21-1 remains timethis gate is closed as shown-in line .505 and the second signal element 'gate 21-2 opens as shown in line 506. I

The first signal element gate 21-1 is opened at the time 2 and remains open until time t under the influence of the matrix connections to the busses 16 made by the resistors 73 to 87. A marking signal element at the serial input gatingtube V8A- to H start-stop'oscillator 25 to the cathode of the gating tube from the voltage divider start-stop oscillator 25 is olf and the to open upon the receipt of negative start pulse, shown will not appear at the cathode. applied to the signal element gatesopen until time t at which VBB of the first signal element gate 21-1. This pulse potential on the cathode of the tube V8B, together with the coincidence voltage on the grid, will pass a pulse to the series circuit comprising the resistor 93 and the ca pacitor 94 connected to the first signal element separate output terminal 13-1. The resistor 93 is of such value as to limit the amplitude of the output pulses. This limiting in amplitude, together with the fact that the input signal elements serve only to gate substantially uniform pulses from the start-stop oscillator 25, insures an accurate and uniform pulse output over the separate circuits at the terminals 13-1 through 13-5.

The second through fifth signal element gates 21-2 through 21-5 operate in similar fashion. If the input signal element at the cathode of the tube V13A is marking, a pulse from the start-stop oscillator 25 is passed through the serial gate 31 comprising the tube V8A to all of the gates 21-1 through 21-5 and it will be passed through the assigned signal element gate. If the signal element at the cathode of V13A is spacing, no pulse is passed through the serial signal gate 31 t the signal element gates, and no output appears at the output terminals .13-1 through 13-5.

At the time t the fifth signal element -gate 21-5 closes, the start gate 29 opens, the oscillator .25 is stopped, and a convert pulse is presented at the convert pulse terminals 37. This pulse originates at the anode of the tube V3A in the frequency divider chain 23 at the time when this anode has just become positive. The transition is differentiated by means of the series circuit comprising a resistor 95 and a capacitor 96 and introduced to the grid of a normally blocked tube V9B constituting the convert pulse generator 35. A positive pulse causes the convert pulse tube V9B to conduct and present a negative going pulse at the terminal 37.

'As stated previously, the circuit arrangement of Fig. 2, when operated ser-sep, is usually fed with serially appearing signals from a transmitting distributor of the type requiring an initiating drive pulse, usually called an eighth pulse. This pulse is obtained originally from another component of the system at a time dependent upon the operation of the system and applied to the drive pulse input terminal 43 for amplification in the voltage amplifying tubes V13'B and V14A. The voltage output of the tube V14A is applied to the pentode tube V15, and a current output is presented at the terminal 41. Sufficient current is then available to operate the relay normally and to control the TD or transmitting distributor when it is connected between the terminal 41 and ground.

Sep-ser operation, Figure 2 With the switch elements in the circuit arrangement of Fig. 2 thrown to the opposite position from that shown, the arrangement of Fig. 2 is in condition for separate to serial, .or sep-ser, operation. The input signal elements are presented over separate wires and are applied to the separate input terminals 15 -1 through 15-5 which are individually connected through switch elements, as shown, to the cathodes .of the tubes V83, VA, V1013, V11A and VllB constituting the signal element gates 21-1 through 21-5. Marking signal elements are represented byvoltages and spacing signal elements are represented by the absence of voltage. After the signal elements representing a code character input terminals -1 through 15-5, a start-pulse is presented across the terminals 11-1 and 11-3. This startpulse is, in turn, applied to the grid of the tube V12A of the input amplifier 33 where it is inverted, amplified and presented through the series capacitor 98 and resistor 9.7 to the grid of the tube V4B of the start gate 29 which is normally conditioned toopen upon the receipt of this ,start pulse. Beforethe start pulse was introduced the mark gate 21-M was opened and a mar was sent'through are presented to the separate 21-5 as shown on lines 10 r the output power amplifier 39 comprising the tubes V1313, V14A and V15. The frequency divider chain 23, in response to the first pulse from the start-stop oscillator 25, closes the mark gate to present a spacing condition at the output of the mark gate and the serial output terminal 17. The letter Y will be used as an example in explaining the operation of the gating elements. This letter Y in the five-unit printer code consists of signal elements 1, 3, and 5 marking. When the signal elements corresponding to the letter Y are applied to the terminals 15-1 through 15-5 minus 20 volts will be applied to the cathodes of the tubes VSB, V10B and V1113, whereas the cathodes of the tube V10A and V11A will have Zero volts applied. The cathode of the mark gate 21-M, which is the tube V9A, is permanently established at minus 20 volts. The anodes of the tubes V9A, V8B, V10A, V10B, V11A, and V1113 constituting mark gate 21-M and the signal element gates 21-1 through 21-5 are all connected together through the medium of the switching elements to a point of a low positive potential derived from a voltage divider network comprising resistors 92-1 and 92-2. A negative start pulse applied between the terminals 11-1 and 11-3 blocks the first stage of the input amplifier 33, cutting off the tube V12A, the anode of which rises to plus volts. A positive transition is then differentiated by a resistor 97 and a capacitor 98 connected in series between the anode of the tube V12A and the grid of the start gate tube V43. The start gate 29 closes, and the start-stop control 27 opens. At practically the same instant the oscillator 25 is started, and the gates 21-1 through 21-5 are successively opened as previously described in connection with ser-sep operation. When any one of the gates 21-M and 21-1 through 21-5 opens there is -20 volts on the cathodes, and since all of the anodes of these tubes are returned to ground, the tube which is open will conduct causing the anode to go to a negative potential value. All of the anodes of the mark gate and signal element gate tubes V9A, VSB, V10A, V10B, V11A and V11B are connected together directly to the grid of the tube V12B forming the second stage of the input amplifier 33. When the grid of the amplifier tube V12B is negative the amplifier is blocked. If there is 0 volts on any of the cathodes of the tubes V813, V10A, V103, V11A and V11B constituting the signal element gates 21-1 through 21-5, the anode thereof cannot go low when a gate opens and, therefore, the grid of the amplifier tube V12B will be at very low positive potential and the second stage of the input amplifier will be conducting.

Referring to Fig. 6, it can be seen that before the time t the marking and spacing elements are introduced to the first through fifth signal element gates 21-1 through mark gate 21-M is always at -20 volts as shown in line 604. Line 601 of Fig. 6 shows the start-pulse as obtained from the first stage of the input amplifier 33 or tube V12A. The tube V12B is blocked as shown before the time t in line 616 because the cathode of the mark gate 21-M is always maintained at -20 volts.

At the time t the mark gate 21-M closes, as shown in line 610, and the second stage of the input amplifier 33, tube V12B, is conducting as shown in line 616. At the time t, the first signal element gate 21-1, tube VSB, opens as shown in line 611, and the cathode is'inspected as shown in line 685. Because the first element of the letter Y in five-unit code is marking, 20 volts is present on the cathode of the first element gate 21-1, and the amplifier tube V12B is therefore blocked as indicated in line 616. At the time t the first signal element gate 21-1 closes, as shown in line 611, and the second signal element gate 21-2 comprising the tube V10A opens as shown in line 612. The cathode of the tube V10A is at zero volts because the second signal element of the letter Y in the five-unit printer code is spacing under 6%5-699. The cathode of the which condition the amplifier tube tubeVlZB is conductingas shown in line 616 of Fig. 6. At the time t the "second signal element gate 212 closes as shown in line 612 and the third signal element gate 21-3 comprising the vacuum tube V10B opens as shown in line 613. The cathode of the tube V10B is at 20 volts because the third signal element of the letter Y in the five-unit code is marking. Therefore, the amplifier tube V12Bis again blocked asshown in line 616.

The other gates operate in like fashion until at the time i the fifth signal element gate closes as shown in line 615 and the mark gate 21-M comprising the tube V9A opens as shown in line 610. The cathode of the tube V9A is always at 20 volts so that the amplifier tube VlZB is blocked as shown in line 616 and remains blocked until the next cycle of operations. The oscillator 25 is stopped, and the start gate 29 is in condition to receive another start pulse. The signal at the anode of the tube V'lZB is coupled by means of the neon N1 to the grid of'the vacuum tube V13A, which is connected by means of a switching element to operate as a normal D- C. triode amplifier delivering the signal to the voltage amplifier tr'iode V14A. The triode V14A in turn drives the current amplifier pentode V15 to produce an output signal of sequentially appearing elements over a single circuit "at the terminal 41- for utilization by a printer,'a relay, or similar type of apparatus.

The start-stop control tube V4A is arranged so that in ose cases in which the required idle conditions do not exist between characters, the tube V4A is conducting. If, for some reason, a gate other than the mark gate 21-M is open, the start-stop control tube 4A will cut ofi leavingthe start-stop oscillator oscillating until the mark gateremains open which is the correct operating condition, causing the tube V4A to conduct and hold the start-stop oscillator 25 from operating.

' It should be noted that the choice of frequency of the start-stop oscillator 25 is dependent upon the width of the character elements, a frequency of operation, and the length of the stop element. A switch can be added to change the values of capacity of the capacitors 45 in order to change the frequency of operation, the length of the stop element, or both as desired.

The switching means S shown in Fig. 1 for reversing the directional mode of operation of the extensor according to the invention has in the interests of clarity been shown in Fig. 2 as simple, double-throw, single-pole switch-elements, having the arms arranged in the ser-sep connection operated together. In accordance with a further aspect of the invention it is preferred that'the connections be automatically made when the extensor is connected to auxiliary apparatus with which it is working, so that the desired operation, that is, sersep or sep-ser, is obtained without any attention on the part of the operating technician. Referring to Fig. 3, there is shown a diagram of plugs having connections for accomplishing this switching and for coupling to the associated telegraph apparatus. At Fig. 311 there is shown the wiring of a ser-sep plug for use in connecting an extensor according to the invention between an incoming telegraph line, for example, and a 5-wire telegraph printer. The 33 pins, numbers 1-33, when plugged into a corresponding socket on the extensor chassis, contact the respective contacts of the switch elements marked S-l through S33 in the diagram of Fig. 2. All connections marked with these same S numbers are connected together at the plug, although they are shown separately in the schematic diagram of Fig. 2 in order to clarify the diagram. Serial input is applied by connections made between pin 23 and pin 26, and the auxiliary input ap paratus and the separate output is taken from pins 3, 6, 9, 12 and 15 to the associated utilization apparatus.

[An operate pulse is applied at pin 29 and the output rethis pulse is obtained at the terminal 41. The

sulting from wherein said serial wherein said 12. remaining pins are wired solely to perform the switch ing function.

The wiring of a sep-ser plug is shown at Fig. 3b.

' This plug has identical pin lay-out to the plug shown is applied by way of pin 23 and ground at pin 17. The

remaining pins are wired solely to perform the switch-j ing function as indicated by the arms in Fig. 2. Obviously, a multipole double throw switch could be installed on the extensor chassis and wired as shown for the switch elements in .Fig. 2. There is a decided advantage, how ever, to have the operator switch the circuit merely by removing and installing the extensor chassis. The invention claimed is:

l. A telegraph extensor including a set of single .circuit serial input terminals, a plurality of separate circuit output terminals, a start-stop oscillator, a serial input gate connected to said oscillator, a plurality of signal element gates individually coupled to said separate output terminals and connected in common to. said serial input. gate, start-stop oscillator and to said signal element gates-to activate the latter in timed succession in response to excitation by said start-stop oscillator, means coupled between said'serial inputtermmals and said start-stop oscillator to start the latter to oscillate at the first transition of a serial signal element train applied to said serial input terminals, and a connection between-said serial input terminals and said serial input gate to operate said serial input gate to pass a pulse from said oscillator to said signal element gate assigned to a sig nal element under consideration in. said train ifsaid signal element under consideration received at.said serial input terminals is of a predetermined nature, thereby to provide an output current at the one of said separate output terminals connected tosaid last-mentioned signal element nal element gate being activated by said timing wave generator. 7

2. A telegraph extensor as defined in claim 1 wherein said serial gate is arranged to pass a relatively narrow pulse from said start-stop oscillator intermediate the extreme limits of the signal element under consideration. 3. A telegraph extensor including a set of single circuit input terminals, a serial electronic gating circuit coupled to said input terminals, a plurality of signal element electronic gating circuits coupled in common to said serial electronic separate circuit output terminals individually coupled to said signal element gating circuits, a timing wave generating circuit arranged ment rate to said serial gating circuit and to apply a timing wave to said signal element gating circuits to ready the same for conduction in timed succession, said serial gating circuit being arranged to pass pulses applied by said timing wave generating circuit to all of 'said signal element gating circuits only in responseto a signal element of one terminals to produce sequentially appearing pulses at said separate circuit output terminals coupled to the signal element gating circuits assigned to said signal elements of said one nature.

4. A telegraph extensor as defined in claim 3 and signal, element gating circuits intermediate the extremities of said signal elements.

5. A telegraph extensor as defined in claim 3 and pulses from said timing wave generating circuit to said signal element gating circuits at substantially the center "of said signal elements.

a timing wave generator coupled to said gate upon said last-mentioned siggating circuit, a plurality of to apply pulses at signal ele.

nature applied to said inputserial gating circuit is arranged to pass said 6. A telegraph extensor as defined in claim 3 and wherein said timing wave generator comprises a startstop oscillator coupled to a binary counting chain and a control circuit coupled to said input terminals and said binary counting chain to start and stop said oscillator. t

7. A telegraph extensor for transposing serially appearing signal elements appearing over a single circuit to sequentially or simultaneously appearing signal elements appearing over a plurality of separate circuits and conversely including a bank of electronic gating devices comprising a plurality of electron discharge de vices having cathode, grid, and anode electrodes, means to apply potentials to said grid electrodes to render the same positive with respect to the associated cathodes in timed succession, separate circuit output terminals individually coupled to the anode electrodes of said electron discharge devices, a single circuit output terminal, a plurality of separate circuit input terminals, a single circuit input terminal, and a switching assembly arranged to connect said separate circuit input terminals individually to the cathode electrodes of said electron discharge devices and said single circuit output terminal in common to the anode electrodes of said electron discharge devices and selectively to couple the cathode electrodes of said electron discharge devices in common to said single circuit input terminals. 8. A telegraph extensor as defined in claim 7 and wherein a further gating circuit is interposed in said common coupling to said single circuit input terminals to couple said cathode electrodes to said single circuit input terminals only in response to applied signal elements of predetermined nature.

9. A telegraph extensor as defined in claim 8 and wherein said further gating circuit comprises a pair of electron discharge structures having cathodes connected in common to said cathode electrodes of said electron discharge devices and control grids, one of said control grids being coupled to said single circuit input terminals and the other being connected to a source of pulses of signal element recurrence rate.

10. A start-stop oscillator circuit arrangement including a monostable reciproconductive circuit having one normally conducting and one normally blocked electron discharge device each having a plurality of electrodes, triggering electron discharge systems individually coupled to said electron discharge devices, a start gating circuit connected to an electrode of said normally conducting electron discharge device to apply a pulse thereto for starting said oscillator, 21 start-stop control circuit connected to the triggering electron discharge system coupled to the normally blocked electron discharge device, said control circuit comprising a normally conducting electron discharge structure holding sa'd oscillator quiescent, a counting circuit coupled to said start-stop oscillator to derive a pulse in response to the sta g of the same, said counting circuit being coupled to said start-stop control circuit to block said electron discharge structure in response to said derived pulse and release said oscillator to continue operation thereof, a pulse generating circuit coupled to said counting circuit to develop a pulse at a predetermined time in response to the continued operation of said oscillator, said pulse generator being coupled to said start-stop control circuit to stop said oscillator upon generation of said developed pulse, and further connections between said pulse generator and another electrode of said normally conducting electron discharge device to force said reciproconductive circuit rapidly to the normal state of conduction of said electron discharge devices.

11. In a pulse signalling system including input terminals, a first gating circuit coupled to said input terminals, a plurality of other gating circuits coupled in common to said first gating circuit, a plurality of separate output terminals individually coupled to said other gating circuits, a timmg wave generating circuit arranged to cycle of operation of said apply pulses at signal element rate to said first gating circuit and toapply a timing wave to said other gating circuits to ready said other circuits for conduction in timed succession, said first gating circu't being arranged to pass pulses applied by said timing wave generating circuit to all of said other gating circuits only in response to the application of a signal element of one nature from said input terminals to said first gating circuit, as a result of which pulses appear in sequence at only those separate output terminals coupled to said other gating circuits to which said pulses from said first gating circuit and said timing wave from said timing wave generating circuit are simultaneously applied.

12. A pulse signalling system as defined in claim ll and wherein said timing wave generating circuit comprises a start-stop oscillator coupled to a binary counting chain and a controicircuit coupled to said input terminals and said binary counting chain to start and stop said oscillator.

13. A telegraph extensor having a monostable multivibrator circuit constituting an oscillator, a frequency dividing network including a plurality of series connected bistable multivibrator circuits coupled to said oscillator and arranged to produce harmonically related waves in response to excitation by said oscillator, a start gate connected to said oscillator and responsive to an input pulse applied thereto to pulse said oscillator to cause said oscillator to become operative for a single cycle, a connection between said network and said start gate to cause said start gate to be held inoperative upon the operation of said network in response to said single cycle of operation of said oscillator, and a start-stop control circuit connected between said network and said oscillator and responsive to the operation of said network in response to said single oscillator to maintain said oscillator operative.

14. An extensor for transposing serially appearing signal elements appearing over a single circuit to sequentially or simultaneously appearing signal elements appearing over a plurality of separate circuits and conversely including abank of gating devices, means to apply potentials to said gating devices to place said gating devices in condition for operation in timed succession, separate circuit output terminals individually coupled to the output circuits of said'gating devices, a single circuit output terminal, a plurality of separate circuit input terminals, a single circuit input terminal, and a switching assembly arranged in one condition to connect said separate circuit input terminals individually to the input circuits of said gating devices and said single circuit output terminal in common to said output circuits of said gating devices and arranged in a second condition to connect said input circuits of said gating devices in common to said single circuit input terminal.

15. A telegraph extensor for transposing serially appearpearing signal elements appearing over a single circuit to sequentially or simultaneously appearing signal elements appearing over a plurality of separate circuits and conversely including a bank of current conducting gating devices each having an input, control and output electrode, means to apply potentials to said control electrodes to place said control electrodes at the proper potentials with respect to said input electrodes to place said devices in condition for conduction in timed succession, separate circuit output terminals individually coupled to said output electrodes, a single circuit input terminal, a plurality of separate circuit input terminals, a single circuit output terminal, and a switching assembly arranged in one position to connect said separate circuit input terminals individually to said input electrodes and said single circuit output terminal in common to said output electrodes and in a second position to connect said single circuit input terminal in common to said input electrodes.

16. A telegraph extensor including a set of single circuit serial input terminals, a plurality of separate circuit output terminals, a plurality of separate circuit input terminals, a set of single circuit serial output terminals, a start-stop :oscillator,'-electronic switching circuitry connected to said oscillator and between said single circuit input terminals .and said separate circuit output terminals selectively cou :pling output pulses of said oscillator in timed sequence to each of said separate circuit output terminals in accordance with signals on said single circuit serial input termi nals, whereby sequentially 'at said separate output terminals corresponding to serialappearing pulses are produced 'ly appearing pulses applied to said single circuit serial input terminals, and a switching assembly included in said switching circuitry and arranged upon being operated .to connect in the alternative said switching circuitry between said separate circuit input terminals and said single circuit output terminals, said switching circuitry being arranged upon the o selectively c timed whereby simultaneously app separate circuit input termi sequence to said single circu ouple said se peration of said switching assembly to parate circuit input terminals in succession to said single circuit output terminals, caring pulses applied to said, nals are selectively appliedvin it serial output terminals.

References Cited in the file of this patent UNITED STATES PATENTS Slayton Jan.-2, 1951 Shenk Mar. 6, 1951 Coley Jan. 20, 1953'. Gloess et al. Apr. 14, 1953 

